Category Archives: science

Breathing very dirty air may boost obesity risk

Beijing smog

Serious air pollution, like this smog over China’s capital city, may increase the risk of obesity.

Air pollution is bad for our lungs. It may not be great for our waistlines either, a new study in rats finds.

China’s capital city of Beijing has some of the worst air pollution in the world. On really bad days, its air can host more than 10 times as many tiny pollutant particles as the World Health Organization says is safe for human health. In a new study, rats breathed in this air. And those rodents gained more weight, and were unhealthier overall, than were rats breathing much cleaner air. The results suggest that exposure to air pollution can raise the risk of becoming extremely overweight.

And, adds Loren Wold, “It is highly likely that this is happening in humans.”

Wold works at Ohio State University in Columbus. There, he studies how air pollution affects the heart. He was not involved in the new study. But he says it agrees with many other studies that have suggested air pollution can affect metabolism, which is how the body breaks down food and uses it for fuel.

Polluted air contains particles of ash, dust and other chemicals. Sometimes these particles are so numerous that they create a thick, dense smog can cuts visibility.

Earlier experiments among 18-year olds in Southern California had linked heavier traffic with higher body mass index (a measure of overweight and obesity). Areas with heavy traffic also tend to have more of those pollutant particles. Another study found that when pregnant mice were exposed to exhaust from diesel engines, their pups grew up to be heavier. The pups also developed more inflammation in their brains.

In the new study, researchers tested how Beijing’s polluted air affects the health of pregnant rats.

Jim Zhang is an environmental scientist at Duke University in Durham, N.C. He and his co-workers put rats in two indoor chambers in Beijing. They piped polluted air from the city directly into one chamber. Air piped into the other chamber went through a filter. That filter removed almost all of the big pollution particles from the air and about two-thirds of the smaller ones. This made the air more like what people breathe in typical U.S. cities and suburbs, Zhang says.

All rats ate the same type and amount of food. But after 19 days, the pregnant rats breathing the heavily polluted air weighed more than the rats breathing the filtered air. They also had higher amounts of cholesterol — a waxy, fatlike substance — in their blood than did the rats breathing filtered air.

Those breathing the dirtier air had higher levels of inflammation. This is a sign of the body responding to tissue damage. These rats also had higher insulin resistance. This means their bodies weren’t responding as well to insulin, a hormone that helps with using sugar for energy. Insulin resistance can lead to diabetes, a dangerous health condition.

Taken together, the scientists say, these symptoms indicate the rats were developing metabolic syndrome. It’s a condition that puts the animals at risk of heart disease and diabetes.

During the experiment, the pregnant rats gave birth. Their pups stayed in the chambers with their mothers. And young rats that breathed in the polluted air were heavier than pups born to moms living in the cleaner air. Like their moms, the pups breathing very polluted air had more inflammation and insulin resistance.

The longer these pups breathed the dirty air, Zhang says, the more unhealthy they became. This suggests that breathing polluted air for a long time can lead to sickness, Zhang says.

It’s not yet clear exactly how air pollution affects rat metabolism. But it seems, Zhang says, to impair how the animals process fat and sugar. Pollution also increases signs of inflammation in the lungs, blood and fat. Zhang says this is probably what led to weight gain in the animals.

Wold says it might be possible to create medicines that reverse the negative health effects of air pollution. But these medicines will take time to develop.

Until then, Zhang and Wold say that paying attention to air pollution levels can help people manage their health risks. On days when pollution levels are high, they recommend that people stay indoors, if possible — or at least avoid tough outdoor exercise

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When will the universe end? Not for at least 2.8 billion years

Cosmic doom

We’re safe for now. The way the universe is expanding, it won’t be tearing itself apart for at least a few billion years.

For those of you only now discovering that such an end was a possibility, here’s a little background. Observations of stars and galaxies indicate that the universe is expanding, and at an increasing rate. Assuming that acceleration stays constant, eventually the stars will die out, everything will drift apart, and the universe will cool into an eternal “heat death”.

But that’s not the only possibility. The acceleration is thought to be due to dark energy, mysterious stuff that permeates the entire universe. If the total amount of dark energy is increasing, the acceleration will also increase, eventually to the point where the very fabric of space-time tears itself apart and the cosmos pops out of existence.

One prediction puts this hypothetical “big rip” scenario 22 billion years in the future. But could it happen sooner? To find out, Diego Sáez-Gómez at the University of Lisbon, Portugal, and his colleagues modelled a variety of scenarios and used the latest expansion data to calculate a likely timeline. The data involved nearby galaxies, supernovae andripples in the density of matter known as baryon acoustic oscillations, all of which are used to measure dark energy.

The team found that the earliest a big rip can occur is at 1.2 times the current age of the universe, which works out to be around 2.8 billion years from now. “We’re safe,” says Sáez-Gómez.

Time equals infinity

And when is the latest it could happen? “The upper bound goes to infinity,” he says. That would mean the rip never comes and we end up with the heat death scenario instead.

Given that the sun isn’t expected to burn out for at least another 5 billion years, it would be surprising if the universe ended so early. But pondering our doom could be a worthwhile exercise anyway, Sáez-Gómez says. Scenarios like the big rip result from a lack of understanding of physics in particular our inability to marry quantum mechanics and general relativity, the theory of gravity. Exploring the possibilities could show us a way forward.

“You learn more about a physical theory by looking at the exotic and extreme cases,” says Robert Caldwell of Dartmouth College in New Hampshire, who helped come up with the big rip idea. He thinks Sáez-Gómez’s lower bound is very conservative, however – the universe is likely to last much longer. Even if it doesn’t, at least we’ve got a good run ahead of us. he says.

Reference: arxiv.org/abs/1602.06211v1

Missing Y chromosome kept us apart from Neanderthals

The Y chromosome is a hindrance

Modern humans diverged from Neanderthals some 600,000 years ago – and a new study shows the Y chromosome might be what kept the two species separate.

It seems we were genetically incompatible with our ancient relatives – and male fetuses conceived through sex with Neanderthal males would have miscarried. We knew that some cross-breeding between us and Neanderthals happened more recently – around 100,000 to 60,000 years ago.

Neanderthal genes have been found in our genomes, on X chromosomes, and have been linked to traits such as skin colour, fertility and even depression and addiction. Now, an analysis of a Y chromosome from a 49,000-year-old male Neanderthal found in El Sidrón, Spain, suggests the chromosome has gone extinct seemingly without leaving any trace in modern humans.

This could simply be because it drifted out of the human gene pool or, as the new study suggests, it could be because genetic differences meant that hybrid offspring who had this chromosome were infertile – a genetic dead end.

Four gene mutations

Fernando Mendez of Stanford University, and his colleagues compared the Neanderthal Y chromosome with that of chimps, and ancient and modern humans.

They found mutations in four genes that could have prevented the passage of Y chromosome down the paternal line to the hybrid children.

“Some of these mutations could have played a role in the loss of Neanderthal Y chromosomes in human populations,” says Mendez.

For example, a mutation in one of the genes, KDM5D that plays a role in cancer suppression, has previously been linked to increased risk of miscarriages as it can elicit an immune response in pregnant mothers.

“That could be one reason why we don’t see Neanderthal Y chromosomes in modern human populations,” says Mark Pagel an evolutionary biologist at the University of Reading.

It could also be one factor keeping the two species as separate species.

The researchers also used the new DNA sequences to estimate the time when the most recent common ancestor of Neanderthal and modern human Y chromosomes existed. They came up with a figure of around 590,000 years ago, which agrees with other estimates for the split of the two groups.

 

Journal reference: The American Journal of Human Genetics, DOI: 10.1016/j.ajhg.2016.02.023

Researchers have written quantum code on a silicon chip for the first time

For the first time, Australian engineers have demonstrated that they can write and manipulate the quantum version of computer code on a silicon microchip. This was done by entangling two quantum bits with the highest accuracy ever recorded, and it means that we can now start to program for the super-powerful quantum computers of the future.

Engineers code regular computers using traditional bits, which can be in one of two states: 1 or 0. Together, two bits create code words that can be used to program complex instructions. But in quantum computing language there’s also the possibility for bits to be in superposition, which means they can be 1 and 0 at the same time. This opens up a vastly more powerful programming language, but until now researchers haven’t been able to figure out how to write it.

Now engineers from the University of New South Wales (UNSW) in Australia have demonstrated that not only can they do this, but they can do it on silicon microchips very similar to the ones that make up today’s computers, which means the technology will be easy and quick to scale up.

So how exactly do you write quantum code? It all comes down to a phenomenon known as quantum entanglement. When two particles are entangled, it basically means that the measurement of one of them will instantly affect the state of its entangled particle, even if it’s thousands of kilometres away.

“This effect is famous for puzzling some of the deepest thinkers in the field, including Albert Einstein, who called it ‘spooky action at a distance’,” said lead researcher Andrea Morello, from the Centre for Quantum Computation and Communication Technology at UNSW. “Einstein was sceptical about entanglement, because it appears to contradict the principles of ‘locality’, which means that objects cannot be instantly influenced from a distance.”

But entanglement has been demonstrated time and time again through something by something known as Bell’s test, which requires engineers to violate Bell’s Inequality Principle. Basically, Bell’s Inequality Principle sets a limit for the amount of correlation there can be between two classical bits – anything above that must be quantum entangled.

“The key aspect of the Bell test is that it is extremely unforgiving: any imperfection in the preparation, manipulation and read-out protocol will cause the particles to fail the test,” said one of the researchers, Juan Pablo Dehollain. “Nevertheless, we have succeeded in passing the test, and we have done so with the highest ‘score’ ever recorded in an experiment.”

In their experiment, the two entangled particles in question were the electron and the nucleus of a single phosphorous atom, which was placed inside a silicon microchip. By entangling the two particles, they made it so that the state of the electron was entirely dependent on the state of the nucleus.

This meant that they expanded on the four possible digital codes that can be made with two traditional bits (00, 01, 10, or 11) to being able to create a much wider set of code words with two entangled bits, such as 00+11, 00-11, 01+10 or 01-10.

CollageEntangled web

“This is, in some sense, the reason why quantum computers can be so much more powerful,” said team member Stephanie Simmons. “With the same number of bits, they allow us to write a computer code that contains many more words, and we can use those extra words to run a different algorithm that reaches the result in a smaller number of steps.”

The next step is to entangle more particles and create more complex quantum code words, so that the team can begin to program an entire quantum computer. All the other pieces are already in place, in large part thanks to another UNSW team, which just last month built the first logic gate in silicon. The material is important, because it’s something we’re already incredibly familiar with building computers out of.

“Now, we have shown beyond any doubt that we can write this code inside a device that resembles the silicon microchips you have on your laptop or your mobile phone,” said Morello. “It’s a real triumph of electrical engineering.”

The research has been published in Nature Nanotechnology.

Teleportation is no longer science fiction – thanks to quantum mechanics scientists

Teleportation is no longer science fiction – thanks to quantum mechanics scientists can teleport information securely from one place to another. The latest episode of Quantum Around You explains how.

When most people think about teleportation, they think about someone disappearing in one spot and appearing in another instantly, Star Trek style. While that would be extremely useful, so far scientists haven’t found a way to do it.

But what they have managed to do is teleport information, and in some ways that’s even cooler.

Quantum teleportation, as its known, is a crucial area of research because it’s the only way humans can transmit information completely securely, with no risk of interception.

To do this, scientists exploit the special characteristics of quantum entanglement. You may have heard of it before, but the latest episode of  University of New South Wales (UNSW)‘s Quantum Around You does an amazing job of breaking down the physics behind the process.

As Associate Professor Andrea Morello, from the School of Electrical Engineering and Telecommunications at UNSW, explains, quantum entanglement is when two electrons become linked and lose their individuality. This means their state or “spin” – which can either be up or down – is defined only as being the opposite of each other.

If you split up two entangled electrons, the person with one can you’re suddenly able to transmit information from one to the other.

That means you could encode information on a single electron (an up spin could mean one thing while a down could mean another, or more commonly, up could represent a ‘1’ in the binary code, while down represents a ‘0’), and the person with the other entangled electron would be able to access that information by looking at what state their electron is in.

So how is that teleportation? What many people don’t realise is that as soon as that information is transmitted, it disappears from the electron of the sender and instantly reappears on the recipient’s electron. Ta da! This is because the sender has to to use another, non-entangled electron to read the information properly, and as soon as they do this the entanglement is lost.

But even though this is a pure example of teleportation, it doesn’t actually contradict Einstein’s theory of relativity, which states nothing can move faster than the speed of light.

Watch the episode above to find out why, and learn more about how scientists are making information disappear and reappear all over the world.

Stress in pregnancy linked to offspring’s asthma risk

Stress carries with it many health problems, including increased risk of heart disease and depression. For pregnant women, however, this list is longer and includes risks for the child – including premature birth, low birth weight and developmental problems. Now, a new study links maternal stress to an increased risk of asthma for offspring.
Stressed pregnant woman
The new study suggests that maternal stress in pregnancy can increase risks of asthma and allergies for the baby.

The study, which was conducted using pregnant mice, is published in the American Journal of Physiology.

It is already well known that keeping stress levels low in pregnancy is important for both mother and baby. Medical News Today recently reported on a study suggesting that yoga during pregnancy can keep maternal stress levels low, preventing anxietythat can lead to postnatal depression.

And even before pregnancy, stress has been linked to an increased risk of infertility.

In this latest study, the researchers, from the Harvard School of Public Health in Boston, MA, found that stress in pregnant mice was linked to an increased risk of allergy-induced asthma in their pups.

According to the Centers for Disease Control and Prevention (CDC), asthma is one of the most common, long-term childhood diseases. In 2010, 1 in 12 adults and 1 in 11 children had asthma. Additionally, in 2009, 3,388 people died from asthma.

Because this is such a widespread, costly condition that has no cure, the prevention of asthma – if possible – is extremely important.

Mother’s stress hormones can cross placenta

The researchers note that glucocorticoids (GCs) are stress hormones that naturally occur in the body and help to keep inflammation down. As such, synthetic versions – such as prednisone, dexamethasone and hydrocortisone – are frequently used in the wake of allergic reactions.

Fast facts about asthma in the US

  • Each year, asthma costs the US $56 billion
  • In 2009, the average yearly cost of care for a child with asthma was $1,039
  • In 2008, asthma caused 10.5 million missed days of school.

However, when released in the body as a stress response, these same GCs can also lead to inflammation and increase allergic responses to environmental irritants, rather than help fight them off.

In pregnant women, GCs are naturally elevated, increasing risk for an adverse allergic response if stress further increases these levels. To further investigate, the team looked at whether the increase in GCs due to maternal stress in pregnant mice could lead to asthma development in the offspring.

One group of pregnant mice was exposed to a single instance of stress while a second group was given dexamethasone to reproduce the effects of stress. Meanwhile, a third group was given a steroid-inhibitor – called metyrapone – that blocks the release of stress hormones.

A fourth group acted as a control group and was not given any interventions.

The researchers found that high concentrations of stress hormones – corticosterone (CORT) – in the mother were able to cross the placenta and increase CORT levels in the fetuses, which could lead to higher risks of developing asthma and allergies.

After birth, the researchers exposed all of the mice to allergens. Commenting on their findings, the researchers say:

“Only the offspring of stressed mothers demonstrated increased asthma susceptibility compared with non-stressed mothers. We also demonstrated that a single episode of stress significantly elevated maternal stress hormone levels.”

They further conclude that their results “indicate that maternal stress can play a role in the initiation of asthma by increasing asthma susceptibility in offspring.”

Study limitations

The study also carries with it certain limitations. Firstly, the team used a stress hormone analog called dexamethasone rather than CORT. Although these two compounds are very similar, the researchers say they are not identical.

Specifically, dexamethasone is more potent and crosses the placenta without degrading, compared with CORT. The researchers say that because of these differences, the use of dexamethasone as an injection may not exactly recreate the effects of rises in CORT following stress.

Additionally, the team notes that their model cannot differentiate between prenatal and postnatal effects of maternal stress, which could have different implications. For example, stress could alter maternal behavior or breast milk, which could prompt changes in the neonatal immune system.

Still, the researchers note that because “inflammation typically includes a stress hormone response, the results also suggest a common pathway by which various injurious exposures during pregnancy might increase offspring susceptibility to asthma.”